This invention relates to an apparatus for printing an image of an original film on a photosensitive material used in the printing process of a press plate, for example in which the image is printed on a sensitive sheet having a photosensitizer applied thereto.
It is well-known that when an image of the original film is printed on the sensitive sheet in a photomechanical process, the printing operation to be carried out is different depending upon the type of sensitive sheet used.
It is more often than not that when a positive-type sensitive sheet is used wherein a non-exposed area thereof comes to be an image through the developing process, a mask for shading only an image area of the original film (hereinafter called as "image erasing mask") is put in contact with the sensitive sheet in place of the original film after printing the image of the original film, and then the exposure process is carried out. An image erasing mask is also used in a color printing process in which some letters or characters are printed with mono color on the outer space of a color picture area. In such a case, when a positive-type sensitive sheet is used, the original film for characters (hereinafter called "character film") is put in contact with the sensitive sheet together with the image erasing mask superposed thereon, and then the printing operation is carried out.
When a negative-type sensitive sheet is used, wherein the exposed area thereof comes to be an image through the developing process, it is necessary to put another mask for shading only the non-image area of the original film (hereinafter called "cut mask") in contact with the sensitive sheet together with the original film before carrying out the exposure process. The cut mask is also generally used when it is necessary to print some characters on the negative-type sensitive sheet in addition to the pattern of the original film. In such a case, a cut mask incorporating characters therein can be used. In view of the requirement for high quality, however, it is preferred that after printing the pattern of the original film, shading, except the character area, is put in contact with the sensitive sheet in place of the original film before carrying out the exposure.
Recently, most photomechanical processes have become increasingly automated. However, in order to meet the requirement for a high degree of accuracy which needs various complicated operations corresponding to the kind or type of sensitive sheet and to the necessity of the character printing in the course of the printing operation, a certain amount of manual operation still seems to be indispensable and actually does not go out of use. Thus there remains an important subject of further automation of the printing operation in the aspects of labor saving in the whole photomechanical process and speedup thereof.